Thank you Lance,=A0 particularly for the 2^nd point= ;

<= o:p>

Thank you Tim, to inform me about the potential over-clocking problem;

= Thank you all for your useful answers.

Regards,

Fabio

<= /span>

From: owner-ibis@eda.org [mailto= :owner-ibis@eda.org] On Behalf Of Lance Wang
Sent: Friday,= July 08, 2011 8:55 PM
To: ibis@eda.org
Subject: [IBIS]= RE: [IBIS-Users] V-T different durations

<= /o:p>

Hi, Fabio,=

I think= 3 important things need to be kept in mind when you generate IBIS buffer m= odel V-T curves:

1. = Starting time point: simulat= ors do differently if you have different time value at starting point for d= ifferent V-T curves. To prevent it, always use the same time Zero point for= all V-T curves, at least for the pair (rising/falling) using the same load= conditions;

2. The end time point: As Tim point= ed out, the most of simulators can handle it correctly when the end points = are different. The most important thing for the end points is to have it st= abled. The simulators will do the different things if the simulators need t= o guess what it is after that.

3. = Have the enoug= h points among transition period. This will give a lot of better simulation= results compared with using the even-spacing points in V-T curves. (it is = what S2ibis produces.)

Hope this helps,

<= /o:p>

Lan= ce Wang

SimDE™ IBIS Validator – Make sure it runs ac= curately. FREE!

<= p class=3DMsoNormal>www.iometh.com/Product/IBISValidator

&= nbsp;

From: owner-= ibis-users@eda.org [mailto:owner-ibis-users@eda.org] On Behalf Of Gr= aham Kus
Sent: Friday, July 08, 2011 1:52 PM
To: 'Fabio= BRINA'; 'ibis-users'
Subject: RE: [IBIS-Users] V-T different dur= ations

Hi Fabio,

One thing = to keep in mind is that S2IBIS defaults to a transient time of 10ns. So you= will need to add the keyword to your s2ibis file to lengthen this time to = accommodate the longest transient time to prevent data truncation.

Regards= ,

-= Graham

Link:

http://www.ece.ncsu.edu/erl= /abstracts/s2ibis2_doc.html

[Sim time] t

t =3D Spice transient s= imulation time

&nbs= p; Optional.

= Default: t =3D 10ns.=

Describes th= e transient simulation time to be used by Spice.

<= p class=3DMsoNormal> <= /p>
From: owner-ibis-users@eda.org [mailto:= owner-ibis-users@eda.org] On Behalf Of Timothy Coyle
Sent:= Friday, July 08, 2011 11:02 AM
To: 'Fabio BRINA'; 'ibis-users'Subject: RE: [IBIS-Users] V-T different durations

Hi Fabio,
I asked this same question a few= months ago and from what I recall the responses were that most modern EDA = tools can properly account for the different VT length durations and it is = not an IBIS spec violation. I was concerned with potential over-clocking si= tuations based upon the different VT duration lengths. I have not done any = follow up testing myself.

I have run into issues with some EDA tools that = in certain situations do have problems with these types of models. So you m= ay want to do some testing at least with one EDA tool to make sure it's not= going to produce unexpected results.

Best,

Tim

= From:= owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org] On Behalf Of= Fabio BRINA
Sent: Friday, July 08, 2011 10:24 AM
To: 'ibis-users'
Subject: [IBIS-Users] V-T different durations

Hello experts,
&n= bsp;
  a simply question (I suppose= !) :

   Can I have different durations for the four V-T wavefor= ms ?

   Till today I generated Rising0, Rising1, Fal= ling0, Falling0 curves
&nbs= p;using the same durations, but Can I have the following situations:
  Rising0 =E0   12 ns duration=
  Rising1 =E0 10ns duration
   Falling0 =E0 8ns duration
    Falling1 =E0 11ns duration
&= nbsp;
   Standard d= oes not preclude it, but can cause problems to user?

Thank you in a= dvance.

Fabio

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